Insertional gene activation by lentiviral and gammaretroviral vectors.
Gammaretroviral and lentiviral vectors are promising tools for gene therapy, but they can be oncogenic. The development of safer vectors depends on a quantitative assay for insertional mutagenesis. Here we report a rapid, inexpensive, and reproducible assay which uses a murine cell line to measure the frequency of interleukin-3 (IL-3)-independent mutants. Lentiviral and gammaretroviral vectors cause insertional mutagenesis at similar frequencies; however, they use different mechanisms. Human immunodeficiency virus (HIV)-based vectors generate mutants by insertion only into the growth hormone receptor (Ghr) locus. The HIV enhancer/promoter is active in the absence of the HIV Tat protein in this locus, and an HIV/Ghr spliced transcript expresses GHR and cells respond to GH. Deletion of the enhancer/promoter in a self-inactivating HIV-based vector prevents this mechanism of insertional mutagenesis. In contrast, gammaretroviral vectors insert into other loci, including IL-3 and genes identified as common insertion sites in the Retroviral Tagged Cancer Gene Database (RTCGD).
Bokhoven
Marieke
M
Infection and Immunity, University College London, Windeyer Building, 46 Cleveland Street, London W1T 2AH, United Kingdom.
Stephen
Sam L
SL
Knight
Sean
S
Gevers
Evelien F
EF
Robinson
Iain C
IC
Takeuchi
Yasuhiro
Y
Collins
Mary K
MK
D000818:Animals; D002460:Cell Line; D017988:Gammaretrovirus / Q000235:genetics*; D015316:Genetic Therapy / Q000009:adverse effects*; D005822:Genetic Vectors / Q000009:adverse effects*; D016086:Lentivirus / Q000235:genetics*; D051379:Mice; D016254:Mutagenesis, Insertional